Proper refractory dry out is key to optimum service life. Dry out, also referred to as bake out, is the process for removing both the mechanical water added during the mixing process and chemical water originally added in manufacturing from the refractory. K licensee hotwork is the pioneer of the convective heating process, which simplifies refractory dryouts and heatups. Api 936, refractory installation quality control inspection and testing monolithic refractory linings and materials, provides installation quality control guidelines for monolithic refractory linings and may be used to supplement owner specifications. There have been significant improvements in castable and plastic refractories over the past 35 years through the selection of better raw materials, improved particle sizing, additives, improved bonding materials and improved manufacturing processes and placement methods. For this comparison, both options begin with the removal of a conventional castable nose ring. The curing and firing of refractory castables densecretes and litecretes. Refractory, or the lining utilized on the interior of rotary kilns, is a critical component in ensuring process efficiency and prolonging the life of a rotary kiln.
May 22, 2019 dry out is the initial heating of castable lining in order to remove retained water from within the refractory castable without adversely affecting its structure or physical properties. Speeding up the process can and has resulted in refractory failures leading to hot spots on the metal coverings after firing of the mainburner. I am agree with ts1979, every refractory lining especially for monolithic castable lining has to cured for 24 hours minimum before dryout process. In the steamgenerating industry, refractory materials are used for filling gaps and openings to help keep the fire inside the fire box, for lining ash hoppers wet and dry that collect ash and slag, and for the protection of lower furnace wall tubes inside fluidized bed, cyclonefired, or refusederived fired boilers. The correct application of heat curing and controlled release of water in the castable is very important for the life time. Controlled heating, through these reactions ensures maximum strength.
Unfortunately, standard refractory dry out schedules, provided by all refractory manufacturers with their products, are difficult to apply to refractory used on a steamgenerating boiler. Pdf in 2002 the commissioning of an ilmenite smelter on the north coast of south africa was extended by three months due to the failure and. Secondary reformer refractory dry out operation ijert. Pdf secondary reformer refractory dry out operation prem. North american refractory and dryout fives in combustion. Dry out design considerations and practices for cryogenic gas plants joe t. Two angled, offset, highvelocity burner heads direct the flames and hot gases to the extreme ends of the car or enclosure while producing circulation patterns for optimum drying, heating and cycle control. One burner unit exists of the mobile burner with the extended nozzle, the combustion fan, regulation flap for the combustion air, the connecting air. Drying out monolithic refractories gulf coast combustion. Materials, equipment, and personnel are qualified by the methods described, and applied refractory quality is closely monitored based on. Refractory dryout is the controlled process of applying heat to a refractory lining to remove water from the lining system without causing damage to the refractory materials. Boiler refractory dry out is to ensure proper drying, curing of refractory applied on furnace and other components. Refractories are inorganic, nonmetallic, porous, and heterogeneous. The combined efforts of refractory manufacturer, installer and dryout contractor result in optimal refractory performance.
Rcf is a refractory ceramic fibre material, also know as asw alumino silicate wool. Refractory mortar is a specially engineered mixture of sand, calcium aluminate, cement, and fireclay. It is the largest temperature drying causes more even heat distribution conglomerate in the west africa and one of the largest in resulting better refractory dry out. Everything you need to know on rotary kiln refractory. Longer period of low temperature drying causes more even heat distribution resulting better refractory dry out. These standard dryout schedules are generic and require temperature monitoring rarely found at power plants, where monitoring. Standard specification for mortar, refractory high. The refractory usually undergoes considerable chemical changes, during initial heating. It does not contain recommendations for any particular refractory for any particular use. Installed refractory linings and castings containing calcium aluminate cement binders should be cured prior to drying. Refractory mortar a selection guide whitacre greer pavers. In most industries it has become widely accepted, the only truly effective means of drying out and heating up refractory is to deploy a heat source, passing large volume of hot gases over the refractory surface, providing an even temperature distribution and re. Heatingup for drying to the operational temperature of the installed monolithic refractory lining shall be carefully carried out because rapid heating causes cracks. Whilst the values and application information in this product data book are typical, they are given for guidance only.
Refractory dry out services is available through hotworks u. Curing is necessary to prevent moisture loss during the setting of the material. Refractory dryout is the controlled process of applying heat to a refractory lining to remove water from the lining system without causing damage to the refractory. Refractory dry out procedures boiler furnace scribd. The requirements for high quality lining is the adequate drying of the material. Discover our comprehensive product range, going beyond monolithics to cover all your refractory needs.
For many refractory installations, the dryout portion of the project can be the most frustrating. Magnesia refractory dryoutmanaging the risk of hydration article pdf available in journal south african institute of mining and metallurgy 1116. Refractory dry out the key to a long refractory life is a dryout using gccs high velocity gas combustion systems. Since calcium aluminate bonded low cement castable refractories were first developed, explosive spalling during dryout has been an ongoing problem for refractory manufacturers, installers, the end user and the service company hired to perform the initial dryout. Harbisonwalker handbook of refractory practice 2005. Refractory dryouts national heat treatment division. The calderys range includes selfflowing castables, dry gunning and shotcreting materials, bricks, ramming and plastic mixes, dry vibrating mixes, taphole clays, injection and grouting products, prefabricated shapes, and more.
It is used to lay firebrick in places that are exposed to extremely high temperature. Formula series dry formulations are mixed only with formula series liquid activator. Boiler refractory dryout courtesy of rentech boiler systems. Refractory curing industrial professionals cheresources. These standard dry out schedules are generic and require temperature monitoring rarely found at power plants, where monitoring. Midland, texas, usa abstract time is often lost during startup of new cryogenic gas plants due to inadequate planning and execution of dry out. It is very much important that proper dry out of secondary reformer refractories as water is the common solvent for mixing refractory material. When mixed together these products exhibit a fast exothermic set and can be he heated at a much faster rate than conventional refractory products. Nonwater soluble refractory mortar is the only refractory mortar that should be used in outdoor applications. Jun 10, 2002 the combined efforts of refractory manufacturer, installer and dry out contractor result in optimal refractory performance.
Pdf drying stages during the heating of highalumina. Dry out procedures for refractory must be completed as per the vendors instruction, which will include a temperature ramping and holding program. Api certified 936 refractory personnel must have knowledge of installation, inspection, testing and repair of refractory linings. An effective dry out procedure, and one carried out in compliance with the manufacturers specification, is the key to ensuring that a furnace operates to both the manufacturers specification and the operators expectations. They are typically composed of oxides of the following materials. The api 936 refractory personnel certification examination is designed to. Refractory dry out procedures free download as pdf file. For the dry out of a refractory lining external high velocity burners are used. Pdf secondary reformer refractory dry out operation. Pdf drying stages during the heating of highalumina, ultra. To optimise the dryout time of your installation, calderys offers a full range of formulations. Exporter of refractory dryout services refractory dry out of incinerator services, refractory dry out of pre heater of cement plant, thermal stabilization of turbine rotor and refractory dryout of convection and breaching section.
This dry out program is given for the average amount of material as an information guide. Our refractory dry out services is consist for the following. The refractory material was not normally thermally cured at the factory. The values and the information given are subject to. Longer period of low temperature drying causes more even heat distribution. Drying or the first heating of the system with a refractory material lining is therefore of great importance. Important considerations for refractory dryouts, startups. Due to the previously mentioned characteristics, nonwater soluble product is the preferred choice for clay flue installations that may vent gas or oil appliances or in any.
Cobane, vice president and general manager hotwork usa lexington, kentucky, usa abstract as monolithic refractory products have become more technically sophisticated and their usage increased, the end userconsumer is more often requiring a turnkey project that. Dry out design considerations and practices for cryogenic. Secondary reformer refractory baking and dry out cycle requires very slow and controlled heating of refractory. Thermal stresses will be produced if heating rate is too rapid. The firewagon mobile system is easily transported to any location where temporary heating is required. Explosive spalling of low cement castable refractories a. Refractory dryout our expertise in these areas ensures maximum flexibility and minimum downtime. The apparent porosity is the volume of the open pores, into which a liquid can penetrate, as a percentage of the total volume of the refractory. Harbisonwalker handbook of refractory practice disclaimer.
The worst case scenario is having to bring the sru down shortly after acid gas has already been. You should apply our company for the different refractory labels, amounts and widths. K licensee hotwork is the pioneer of the convective heating process, which simplifies refractory dry outs and heatups. It is not intended as, and should not be taken as, a warranty of any kind, including but not limited to a warranty of. These external burners are fired with light weight oilgas and will be installed in openings like manholes or doors.
Here, well discuss everything you need to know about refractory, including how it works, the different types, and best practices for preventative care. The secondary reformer having monolithic refractory material contain water or water based liquid which are needed to place the material and help the setting. In addition to being resistant to thermal stress and other elements induced by heat, refractories are usually required to withstand physical wear and corrosion. It is not uncommon for moisture to be absorbed by the refractory during final stages of inshop fabrication, transit to the job site, and before the upstream combustion products are first passed through the unit. The information presented in this book is for general educational use only. This necessitates another sru outage to affect repairs and another dry out procedure, costing another 4 to 6 days of downtime. The refractory mortar is utilized only to build fire places and shall not be applied on hot faces. Astm f1097 17 standard specification for mortar, refractory. New challenges have been identified over recent decades regarding the increasing complexity of the dry out step of refractory castables, mainly due to the advances on the particle size. Dry out, also referred to as bake out, is the process for removing both the mechanical water added during the mixing process and chemical water originally. It is very much important that proper dry out of secondary reformer refractories. I am agree with ts1979, every refractory lining especially for monolithic castable lining has to cured for 24 hours minimum before dry out process.
Water is a commonly used ingredient, which is used to mix mortars, rams, castables, cements that is used for installation. Combustion air blower with capacity up to 5000 nm3hr. Dry out must not be confused with curing, which is the process of keeping the refractory material wet or the surrounding atmosphere humid for. There are two main types of refractory mortars available. Heating procedure for castable refractories kiltas refrakter. Any deviation from this program may result in the refractory cracking or even failure falling down. Unfortunately, standard refractory dryout schedules, provided by all refractory manufacturers with their products, are difficult to apply to refractory used on a steamgenerating boiler. Drying refractory in steamgenerating boilers insulation outlook.
National heat has over ten years of experience undertaking refractory dry outs for many clients around australia. The curing and firing of refractory castables darley firebrick. The dryout cycle can be programmed into the control system. While heating, there must be free air flow over the system to ensure removal of moisture. While heating, there must be free air flow over the system to ensure. Drying refractory in steamgenerating boilers insulation. Various capacity of oil and gas burners, including high velocity burners up to 5,000,000 kcalhr. Newly installed refractory re quire a carefully controlled initial heating. Thermbonds formula series refractory products consist of two parts, a dry formulation and a liquid activator. Dry out is the initial heating of castable lining in order to remove retained water from within the refractory castable without adversely affecting its structure or physical properties. Dry out the industry always demands higher quality monolithic refractory linings.
It is very much important that proper dry out of secondary reformer refractories as water is the common solvent for mixing. A high velocity hot air burner is recommendable for heatingup. Refractory has always been an integral part of steamgenerating boilers. By utilizing stateoftheart equipment, including digital process controllers, fully proportional fuel actuators, and solidstate features, our engineers are able to provide flexible service that meets the most demanding of specifications. If the initi al heating is carried out to rapidly and or with local hot spot, then diffrent rates of. Pdf magnesia refractory dryoutmanaging the risk of hydration. For the dryout of a refractory lining external high velocity burners are used. Pdf magnesia refractory dryoutmanaging the risk of. Sulphur plant and tail gas treating unit startup and. The excess air burner is particularly suited to the application of high excess air combustion to dry out refractory. It looks like the work is completed, the vessel looks brand new, and there are always intense pressures to fire it up and get production ramped back up after a. Ammonia and urea complex important that proper dry out of secondary reformer includes.
Premixed refractory mortars may wash out even after drying. Refractory experience in circulating fluidized bed combustors. Table 1 compares installation times over a 24month life cycle for sifca nose blocks and a conventional refractory castable nose ring. The dry ingredients are then moistened to the texture of stiff cookie dough, packed into a form, and allowed to dry thoroughly before bake out. A refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures.